1. Field of Invention
This invention relates to a liquid crystal display device, especially to a liquid crystal display device with partial display function, in which only a necessary part of the display screen of the display device is used for display.
2. Description of Related Art
Further reduction of the power consumption has been sought for the portable devices. Accordingly, the display device of such devices also requires low power consumption. There has been display devices with partial display function, in which only a necessary part of the screen is used for display during a power saving mode, in order to respond to the demand for the lower power consumption. The partial display is achieved by setting a special area for displaying a fixed pattern, for example, the amount of remaining battery or the time in a display region of a liquid crystal display device. A plurality of pixels for displaying an arbitrary pattern is disposed in a matrix configuration in the display region other than the special area designated for the partial display. Only the special region for the fixed pattern is operated to display the fixed pattern during the power saving period.
A plurality of display areas that can be operated and controlled individually may be configured in the same display panel, so that only a part of the display region can be operated for making a display depending on the demand. However, the configuration with such predetermined divided areas independently controlled can not fulfill the demand of displaying an arbitrary pattern at an arbitrary position during the power saving period.
Also, the content and the position of the display during the power saving period vary depending on the type of the host device of the display device. Therefore, different kinds of display devices are developed independently according to the configuration of the display panel and driver circuit of each device.
A matrix type display device accommodates the display of an arbitrary pattern at an arbitrary position. However, the entire display region should be under the normal operation even if only the partial display is required. Therefore, this is not an effective way to lower the power consumption.